In my U.S. Pat. No. 4,659,260, there is shown a trench box comprised of spaced, parallel side walls and end walls pivotally connected to the ends of the side walls for holding the side walls in spaced, parallel relation. The upper longitudinal edges of the side walls and end walls are flat and, as a consequence, when the trench box is disposed in a trench with the upper longitudinal edges below ground level, it often happens that large rocks fall from the sides of the trench onto the upper edges where they accumulate together with loose dirt in considerable amounts. The buildup of rock and dirt poses the possibility of serious injury to persons working within the trench box. It is the purpose of this invention to so construct the trench box as to minimize the accumulation of rocks and dirt at the upper edges of the side walls and end walls so that it descends to the outer or inner side without accumulating on the upper edges.